Alan Stern wrote:
> I suggest you just forget about acquiring the lock in status_dequeue() and
> simply leave it as
>
> 	del_timer_sync (&hcd->rh_timer);
> 	hcd->rh_timer.data = 0;

Hmm, so if some other URB gets queued in that window,
it'll get trashed?  Unlikely .. the clean fix would be
making the status endpoint have a real URB queue.

I combined your suggested change with two others:
(a) protect the status-unlink and control completion
    handlers against IRQs [ the cases Duncan noted]
(b) use mod_timer to retrigger the timer, instead of the
    heavy weight path.